Adverse reactions to foods are one of the most controversial and confusing areas in clinical immunology. The Federal Register in 1983 estimated 15% of the population, amounting to approximately 34 million people, may be allergic to some food ingredients. Millions of dollars have been spent on unproven diagnostic and therapeutic procedures for food allergies. Until recently very little of the scientific literature addressed this health concern. Soy, milk, wheat, peanut, and egg have proven to be the offending food in approximately 90% of children with documented adverse food reactions. Because soy proteins are being utilized increasingly in food products, the potential for sensitization and adverse reactions is also increasing. The purpose of this project is to: 1) determine the predominate allergens in soy protein, and 2) characterize immunologically- mediated adverse reactions to these proteins. The immune response to soy proteins in patients with soy hypersensitivity diagnosed by double-blind placebo-controlled food challenges (DBPCFC) will be assessed by in vitro analyses of their sera. The soy proteins will be identified and purified by SDS-polyacrylamide electrophoresis, gel filtration, fast protein liquid chromatography (FPLC) and sequence analysis. Enzyme-linked immunosorbent assays (ELISA), immunoblotting and monoclonal antibodies will be used to characterize the immune response to these antigens. Five-year follow-up studies in this project are designed to evaluate the clinical course and significance of soy hypersensitivity reactions. The study also addresses the relevance of cross-reacting antigens among soy and the rest of the legumes. By studying adverse reactions to soy protein, one of the major causes of food hypersensitivity reactions, scientific information concerning antigen identification, characterization and the immunologic response, can be applied to investigations into adverse reactions in other major food groups.